A narcoleptic person; a person with narcolepsy.
An STD waiting to happen Lucky
A man who is sleeping with a lot of women can be a simultaneous dater. However, if a man is dating or married to another woman and is sleeping with a lot of women is a cheater. It's the same with women, if she sleeps with a lot of men. Also he can be called a manwhore or player.
It would cost a LOT of money, but it's possible. Unlikely, though. If you're that suspicious, why not confront him?
booser
chatterbox
a cab
Chihuahua pups do of course
Narcoleptic
Snorlax
A Krillin.
A man.